1. Technical Field
The present invention relates to a drive shaft torque controlling apparatus and a method therefor for use in a vehicle having a power transmission mechanism for converting a driving force from an engine through an automatic transmission and transmitting the driving force to a wheel shaft of the vehicle
The present invention relates to a drive shaft torque controlling apparatus and a method therefor for controlling a drive shaft torque for used in a vehicle in which an engine is connected to a multi-stepped automatic transmission through a torque converter, in particularly to the drive shaft torque controlling apparatus in which a torque fluctuation (gear shift jolt) caused during the gear shift can be reduced
2. Prior Art
In a prior art technique, in an automobile comprising a system for converting a rotation speed of an engine through an automatic transmission (AT) and for transmitting to a wheel shaft of the automobile, using an input shaft speed of the automatic transmission a control of the above converting system is performed.
In the above controlling apparatus, a disc having a groove which is carved at outer periphery is settled on an input shaft of the automatic transmission, a rotation period etc. of the groove is detected by an electromagnetic pickup (turbine sensor) and the input shaft speed of the automatic transmission is measured. Further, using the measured input shaft speed, the engine and the automatic transmission can be controlled.
In this prior art technique, since it is necessary to provide the disc and the turbine sensor so as to detect the input shaft speed of the automatic transmission, it have drawbacks that it requires a suitable cost for manufacturing the automobile and the weight of the automobile becomes to increase.
Further, so as to dissolve the above drawbacks, it is considered about a method in which using the information of a throttle opening degree and an engine speed etc., several characteristic maps and further the executing formulas, thereby the input shaft speed is assumed.
However, in the above stated method, when a torque being required for driving an engine accessory, for example, a compressor and an alternator of an air-conditioning means and a hydraulic pressure pump for use in a power steering etc., namely an accessory torque is changed in response to a load fluctuation of the engine, in accordance with an affect of the accessory torque, there appears a case in which the engine torque becomes not equal to an input torque (pump torque) of the torque converter.
As a result, it causes a problem that the more in a low speed and a low load operation area of the automobile, the more a ratio between the accessory toque and the engine torque becomes large, thereby an accuracy about the above stated assumed input shaft speed becomes low.
Further, in the other prior art techniques, so as to reduce the gear shift jolt (torque fluctuation) in a multi-stepped automatic transmission of a power transmission mechanism of an automobile, techniques are disclosed, for example, in Japanese patent laid-open publication No. 254,256/1988 and/or Japanese patent laid-open publication No. 4,544/1989.
In the former prior art technique, an ignition period delay angle amount between a starting period and a finishing period of the gear shift has stored in advance in a memory. When an input shaft speed of the multi-stepped automatic transmission becomes to a speed for judging a predetermined gear shift starting speed, it judges as a gear shift starting.
Besides, when the input shaft speed of the multi-stepped automatic transmission becomes to a speed for judging a predetermined gear shift finishing speed, it judges as a gear shift finishing. The ignition period between two periods is formed to slow with a delay angle amount part which has stored in the memory, thereby the gear shift jolt has reduced.
Further, in the latter prior art technique, an engine torque reduction amount between the starting time and the finishing time of the gear shift has stored in advance in a memory, the starting time and the finishing time of the gear shift is grasped by the change of an input/output rotation velocity ratio between the input shaft side and the output shaft side of the multi-stepped automatic transmission, the engine torque between two periods is reduced to a reduction amount part which has stored in the memory, thereby the gear shift jolt has reduced.
In each of the above stated prior techniques, the reduction amount part during the gear shift in the operation amount in which the engine torque is able to reduce the engine torque has stored at every gear shift step in advance in the memory, and according to the reduction amount part which has stored in the memory the engine torque during the gear shift is controlled according to an open controlling method.
By the way, since the gear shift jolt differs from a delicate difference in an individual multi-stepped automatic transmission and the controlling mechanism of the automatic transmission, therefore at every automobile it is necessary to search the reduction amount part of the engine torque etc. at every gear shift step, thereby it has a drawback that it is necessary to take a considerable time.
Further, even when the time is spent so as to reduce an amount part of the engine torque at every gear shift step and the searched reduction amount part is settled into the memory, by the change in time of the automatic transmission etc. it has a drawback that little by little the reduction of the gear shift jolt can not fully carried out.
Then, so as to solve the above stated drawbacks, the technique has proposed in Japanese patent laid-open 241,773/1992. In this technique, a torque sensor is provided on a drive shaft which is an output shaft of a multi-stepped automatic transmission, an output from this torque sensor is feedback-controlled so as to perform a reference drive shaft torque determined in response to an operation condition.
As a kind of this torque sensor, for example, there is a sensor in which so as to measure a twist amount in the drive shaft a strain gauge is provided fixedly to the drive shaft which rotates at a high speed, and a transformation amount is detected at a non-contact state.
However, in the above technique shown in Japanese patent laid-open No. 241,773/1992, it is necessary to provide the torque sensor and it causes a problem that it requires a very high cost. In particularly, during the running of the automobile, it is very difficult to read on the transformation amount of the strain gauge which is provided fixedly to the drive shaft being rotated at a high speed. Further, so as to detect surely the drive shaft torque, it is necessary to employ a very large and high cost torque sensor.